This invention pertains to a process for the preparation of one class of fungicidal oxazolidinone, the 2,4-oxazolidinediones, and intermediate triazole or imidazole carboxylates.
Fungicides that effectively control plant diseases are in constant demand by growers. Plant diseases are highly destructive, difficult to control and quickly develop resistance to commercial fungicides. U.S. Pat. No. 4,957,933 and Synthesis 1981, 38-40 disclose the preparation of 2,4-oxazolidinedione fungicides by treatment of N-hydroxy-2-hydroxyhydroxamic acids with 1,1'-carbonyldiimidazole to form dioxazinediones, and subsequent treatment of the dioxazinediones with phenylhydrazine. WO 90/12791 discloses the preparation of 2,4-oxazolidinediones from 2-thioxooxazolidin-4-ones by desulfurization. However, there is a need for a more efficient process. The present invention provides a new efficient process for the preparation of 2,4-oxazolidinediones.